The invention relates to a robot with drive electronics arranged in distributed manner.
DE 198 46 960 A1 discloses a handling device on a plastics processing machine with on the latter drive motors associated in conventional manner with the parts to be driven, as well as a central control console on which are located both a central feed unit for supplying power to the drive motors and a central control unit for supplying the drive motors with control information.
It has repeatedly been proposed in the case of a robot to position electronic components, particularly components of the drive electronics, such as inverters, servo amplifiers, power semiconductors, drive circuits, ammeters and regulating circuits in distributed manner on the robot structure instead of centrally in a base or separate switch cabinet. As such power electronics generate heat, the heat dissipation problem arises. In view of the fact that the robot structure and the robot carrying elements are made from metal and the latter has a good thermal conductivity, it has been proposed that the power electronics be connected in good heat conducting manner to the robot structure or a gearbox and to dissipate or remove heat via the latter. The disadvantage is that the materials used have a considerable thermal expansion coefficient and therefore can lead to the heating of the robot structure or to different temperatures as a function of the loading condition and consequently to mechanical and geometrical changes. There can also be an increase in the motor temperature, which can lead to a power reduction and increased hazards in the case of contact, as well as to the gear temperature leading to a change in the lubricant and therefore to a reduction in the load carrying capacity and service life.
The same applies for the remote control device in the form of a manipulator according to DE 40 19 217 C2, where a printed circuit carrying electronic components is connected in heat conducting manner by means of the support to a metal base. Thus, here again the heat is dissipated by means of the supporting structure.
Therefore the problem of the invention is to provide an improved robot, whilst avoiding the indicated disadvantages.
According to the invention the set problem is solved in the case of a robot of the aforementioned type in that each drive electronics is thermally insulated with respect to the robot structure and is provided with a cooling device.
Thus, according to the invention the heat generated by the drive electronics distributed over the robot structure in the form of a drive amplifier is not introduced into the robot structure or parts thereof and instead is removed via the cooling device, which is separate to the robot structure, directly into the environment, so that there are no mechanical and geometrical changes to the robot structure due to the thermal expansion coefficients of the material thereof.
According to a preferred development each drive electronics is also mechanically connected to a passive cooling device associated therewith and in particular each drive electronics is held on the robot by means of its cooling device.
The cooling device can be constructed in different ways. However, in a preferred development the cooling device has a cooling body, particularly with cooling ribs or plates.
According to preferred developments of the invention, the cooling body has a fastening edge and by means thereof is fastened to the robot and the cooling device is in particular secured to the robot accompanied by the interposing of a thermal insulator. From the outset it is also possible for the fastening edge to be thermally insulated against the cooling body. In this case no separate thermal insulation is required. The thermal insulation can also be integrated into the fastening edge on the cooling body.
So that the complete robot contour takes not take up an excessive amount of space as a result of the decentral distribution of drive electronics thereon, particularly on the rocker arm and at the same time to utilize the contour and shape resulting from the necessary construction of the robot structure or the individual mechanical robot elements, according to a further development of the invention a drive electronics projects into a recess or a cavity of the robot structure and then fulfils the function of a housing (of a conventional control cabinet) and therefore mechanically protects and electrically shields the drive electronics, thereby ensuring a corresponding protective system particularly according to IP 67, so that the drive electronics can be constructed in casing-free manner, without any complicated casing.
According to another preferred development the mechanical connection of the drive electronics, which can take place by means of the fastening edge of the cooling device to the robot structure is separated from the electrical contacting of the drive electronics with its electric power supply lines. IN a preferred development a breadboard connected to the supply cables is provided having plug contacts by means of which the drive electronics is electrically contacted.
Alternatively either the breadboard is connected directly to the robot structure or the cooling device is fastened, whilst interposing the breadboard, with the latter to the robot structure.
As stated, the drive electronics in particular include power semiconductors and the circuit parts directly associated therewith such as drive units, ammeters and a microprocessor, which generates PWM signals, which implements the current regulation, the necessary monitoring and communications with the control means. An intermediate circuit supply unit can be implemented both centrally, e.g. in the drive box on the carousel or distributed over all the drive electronics. The invention permits a cost saving, open construction of the drive amplifier and the use of inexpensive connectors for connection to the back plane. For the cables running in the interior and the connectors it is possible to use inexpensive constructions. As a result of the plugging principle a simple replaceability of the drive amplifier is possible and servicing is greatly facilitated. It is also possible for two or three low power drive amplifiers to be mechanically combined into a unit, which leads to cost and space savings through the omission or joint use of some parts.